I made a fairly inexpensive fuel pressure tester that works great.  How?  I
bought the least expensive oil pressure gauge I could find (about 8 bucks)
and used a couple of brass fittings to get to 1/4 inch hose barb.  I then
just used a piece of 1/4 inch fuel line to connect to the test T at the
engine.  I've used this setup for over 10 years on several injected busses
and it works great.  Good Luck.
Steve Sandlin
84 Wolfsburg Westy
79 Transporter
00 New Beetle